<template>
    <div class="standard-table">
        <div class="alert">
            <a-alert type="info" :show-icon="true">
                <div slot="message">
                    已选择&nbsp;<a style="font-weight: 600">{{ selectedRows.length }}</a>&nbsp;&nbsp;
                    <template v-for="(item, index) in needTotalList" v-if="item.needTotal">
                        {{ item.title }} 总计&nbsp;
                        <a :key="index" style="font-weight: 600">
                            {{ item.customRender ? item.customRender(item.total) : item.total }}
                        </a>&nbsp;&nbsp;
                    </template>
                    <a style="margin-left: 24px" @click="onClearSelected">清空</a>
                </div>
            </a-alert>
        </div>
        <a-table :size="size" :bordered="bordered" :loading="loading" :columns="columns"
            :dataSource="current" :rowKey="rowKey" :pagination="pagination"
            :rowSelection="{ selectedRowKeys: selectedRowKeys, onChange: updateSelect }">
        </a-table>
    </div>
</template>

<script>
export default {
    name: "StandardTable",
    // props: ['bordered', 'loading', 'columns', 'data', 'rowKey', 'pagination', 'selectedRows'],
    props: {

        /**
         * 数据加载函数，返回值必须是 Promise
         * 默认情况下必须传递 data 参数；
         *    如果使用本地数据渲染表格，业务代码中将获取本地数据包装为 Promise 即可。
         *
         * currentData 用于向外暴露表格当前渲染的数据，
         * 业务开发中也可以直接修改 currentData，从而重新渲染表格（仅推荐用于客户端排序、数据过滤等厂景）
         */
        data: {
            type: Function,
            required: true
        },
        dataSource: {
            type: Array,
            default() {
                return []
            }
        },
        columns: {
            type: Array,
            required: true
        },
        /*      pagination: {
                type: Object,
                default () {
                  return {}
                }
              },*/
        pageSize: {
            type: Number,
            default: 10
        },
        pageNum: {
            type: Number,
            default: 1
        },
        pageSizeOptions: {
            type: Array,
            default() {
                return ['10', '20', '30', '40', '50']
            }
        },
        responseParamsName: {
            type: Object,
            default() {
                return {}
            }
        },
        bordered: {
            type: Boolean,
            default: false
        },
        /**
         * 表格大小风格，default, middle, small
         */
        size: {
            type: String,
            default: 'default'
        },
        rowKey: {
            type: String,
            default: ''
        },
        selectedRows: {
            type: Array,
            default: null
        }
    },
    data() {
        return {
            needTotalList: [],
            selectedRowKeys: [],

            loading: true,

            total: 0,
            pageNumber: this.pageNum,
            currentPageSize: this.pageSize,
            defaultCurrent: 1,
            sortParams: {},

            current: [],
            pagination: {},
            paramsName: {},
        }
    },
    created() {
        //数据请求参数配置
        this.paramsName = Object.assign(
            {},
            {
                pageNumber: "pageNo",
                pageSize: "pageSize",
                total: "totalCount",
                results: "data",
                sortColumns: "sortColumns"
            },
            this.responseParamsName
        );

        this.needTotalList = this.initTotalList(this.columns)

        // load data
        this.loadData({ pageNum: this.pageNumber })
    },
    methods: {
        updateSelect(selectedRowKeys, selectedRows) {
            this.selectedRowKeys = selectedRowKeys
            let list = this.needTotalList
            this.needTotalList = list.map(item => {
                return {
                    ...item,
                    total: selectedRows.reduce((sum, val) => {
                        return sum + val[item.dataIndex]
                    }, 0)
                }
            })
            this.$emit('change', selectedRowKeys, selectedRows)
        },
        initTotalList(columns) {
            const totalList = []
            columns.forEach(column => {
                if (column.needTotal) {
                    totalList.push({ ...column, total: 0 })
                }
            })
            return totalList
        },

        loadData(params) {
            let that = this
            that.loading = true
            params = Object.assign({}, params)
            const remoteParams = Object.assign({}, that.sortParams)
            remoteParams[that.paramsName.pageNumber] = params.pageNum || that.pageNumber
            remoteParams[that.paramsName.pageSize] = params.pageSize || that.currentPageSize

            if (params.pageNum) {
                that.pageNumber = params.pageNum
            }
            if (params.pageSize) {
                that.currentPageSize = params.pageSize
            }

            let dataPromise = that.data(remoteParams)

            dataPromise.then(response => {
                if (!response) {
                    that.loading = false
                    return
                }
                let results = response[that.paramsName.results]
                results = (results instanceof Array && results) || []

                that.current = results

                that.$emit("update:currentData", that.current.slice())
                that.$emit("dataloaded", that.current.slice())

                that.total = response[that.paramsName.total] * 1
                that.pagination = that.pager()
                that.loading = false
            }, () => {
                // error callback
                that.loading = false
            })
        },
        // eslint-disable-next-line
        onPagerChange(page, pageSize) {
            this.pageNumber = page
            this.loadData({ pageNum: page })
        },
        onPagerSizeChange(current, size) {
            this.currentPageSize = size
            /*
            if (current === this.pageNumber) this.loadData()
            console.log('page-size-change', current, size)
            */
        },
        onClearSelected() {
            this.selectedRowKeys = []
            this.updateSelect([], [])
        },
        pager() {
            return {
                total: this.total,
                showTotal: total => `共有 ${total} 条`,
                showSizeChanger: true,
                pageSizeOptions: this.pageSizeOptions,
                pageSize: this.pageSize,
                defaultCurrent: this.defaultCurrent,
                onChange: this.onPagerChange,
                onShowSizeChange: this.onPagerSizeChange
            }
        }
    },
    watch: {
        'selectedRows': function (selectedRows) {
            this.needTotalList = this.needTotalList.map(item => {
                return {
                    ...item,
                    total: selectedRows.reduce((sum, val) => {
                        return sum + val[item.dataIndex]
                    }, 0)
                }
            })
        }
    }
}
</script>

<style scoped>
.alert {
    margin-bottom: 16px;
}
</style>